God Works in Mysterious Ways

The idea of an unknowable God is terribly convenient, diabolically clever, and handy in a clinch. Having an unknowable God means that powerful, greedy, and ambitious men can make fast and loose with doctrine as it suits their purposes. An unknowable God is the power broker's best friend. If God is unknown, and his methods unknowable, interpretation is up for grabs.
Most people hardly realize that the entire Christian doctrine was invented over almost 1500 years by various groups of men representing the heirarchy of the Catholic Church. The truth of this is easily demonstrated by the fact that Popes and priests could once marry and celebacy was decided upon for the clergy rather long after the fact. The holy trinity didn't even exist until a thousand years after the death of Christ, and it took rather a long time and bloody fighting between opposing sides before it was decided whether Christ was mortal or the son of God. Christianity was hardly a fully evolved belief structure that sprang full grown from the head of Christ. When people didn't buy into the doctrine they were either burned at the stake (like the Cathars) or broke off from the Church and started an entirely new interpretation (like Martin Luther). Of course, if one chose to follow Martin Luther one was expected to buy wholeheartedly into his doctrine, which, of course, was the only correct one because he had God on his side that week.
Judaism (same God, different episode) describes a God who is a little more knowable. When the Hebrews messed with God, they heard about it later. God would send plagues or locusts or floods when he was pissed-off. He destroyed cities, turned people into pillars of salt, killed innocent Egyptian children, spoke from burning bushes, caused people to wander hopelessly in the wilderness, and tested Abraham by telling him to kill his son just to see if he'd do it. Vengeance is mine sayeth the Lord. God didn't hesitate to make himself clear when necessary.
From Judaism sprung Christianity, and a God given even less to social interaction. We could debate endlessly why this happened, but I tend to believe that its roots are firmly planted in practical matters inherent in the era in which Christianity began and flourished. Thanks to the Roman Empire, there were wonderful roads, established trading routes, and pretty reliable means of communication and transportation. People were coming and going all the time and information was able to be disseminated with relative timeliness and ease. Christianity spread because the Roman Empire was huge, diverse, and wonderfully efficient. Otherwise, it may never have gone any further than the arrid deserts where it was born. Peter would have never made it to Rome or even out of Judea if the Romans hadn't been marvelous engineers.
Henceforth, wherever there were Romans (and they were pretty much everywhere) there were disciples of Christ spreading the word. In historical terms, it didn't take long before the Roman power structure began to see that Christianity could be rather useful to them and figure out how to pervert the entire business to suit their purposes. They threw some Christians to the lions for awhile, but that was before they took the time to examine it closely enough to recognize its potential as the friend of the rich and powerful. Christians, after all, were all about martyrdom and the meek inheriting the earth and whatnot. The weak and powerless believed that they would have a place in heaven just as surely as the rich and powerful where they would be freed from all their earthly torment and spend the rest of eternity getting to know someone they spent a great deal of time worshipping from afar. This was an open invitation to assure that they stayed weak and powerless.
So, down the road, the Emperor Constantine figured out a way to make the whole thing work by claiming to have seen a flaming cross in the sky at a pivitol moment during an important battle, and presto, Rome is Christian. I imagine that if he had lost the battle he would have claimed that the flaming cross was a message telling him to go Christian or get his ass kicked; either way, it worked. The power structure became Christian and the real fun began. Since they didn't have much to go on and God was, after all, unknowable, it was perfectly reasonable that the powers that were (who were best suited to the business given their superior status and education) should dream up some doctrine that fortified their positions and kept anyone who might oppose them in a happy state of poverty, ignorance, and most important, meekness. It worked beautifully because they could tell people that they would inherit the earth while simultaneously taxing them into even more grueling poverty and increasing their revenues by letting the rich buy their way into forgiveness and heaven with large gifts to the church. The Egyptians and Greeks believed that the deeds of one's entire life were weighed out upon one's death and if the bad outweighed the good, the afterlife was not destined to be a walk on the beach. In Christianity, one's lifetime of evils could be washed away with a heartfelt confession and a few Hail Marys, and Bob's your uncle...you are sitting on the right hand of God. This made it terribly convenient for ambitious and greedy men who wanted to engage in avarice, suck the life out of the faithful peasants, knock a piece off of their neighbors' wives, and still hedge their bets.
The ability to create new doctrine and interpret the desires of an unknowable God came in handy when the riffraff became testy. If they got a little out of hand, it was a simple business to claim to understand what the unknowable God wanted, call up some fanatics, burn a few heretics and witches, and scare the rowdys back into line.
The West, being all about expansion and increasing the power base, went here and there and to the New World, converting all the natives wherever they went. Having the Roman legacy of better weapons and technology, it was a simple enough business to perpetrate geonicide wherever necessary until everyone was either saved or dead. Either way, hapless aboriginals were thoroughly subjugated.
The unknowable God is still solidly in the firmament because we are still the children of the Roman Empire. Its laws, language, political structure, (borrowed with some changes from the Greeks), and empirical vision still dominate the world. If anything, the Roman Empire is bigger than it ever was and as long as there are men who can recognize that the religions of the unknowable God are a useful tool for the purpose of domination, and as long as there are frightened and weak people who will allow themselves to be dominated by them, they will endure.